WASHINGTON — President Obama will return an ambassador to Syria, ending a four-year cold shoulder to the Damascus regime.

The move reinforces Obama’s determination, outlined in his Cairo speech earlier this month, to deepen America’s role in the Middle East as he seeks to broker peace among Israel and its Arab neighbors and improve US relations in the region.

“The president believes that diplomatic engagement helps serve our interests, and that the current policy didn’t make sense,” said a senior administration official.

Washington withdrew its ambassador from Syria in 2005 to protest Syria’s suspected role in the assassination of former Lebanese Prime Minister Rafik al-Hariri.